Empty slice generates NOT IN(NULL) SQL statement

[Julusian]

Follow up to #61

I have hit an issue with the decided upon solution for #61.

When the query is built as WHERE id IN (NULL) I get 0 rows as I would expect, but if the query is WHERE id NOT IN (NULL) I also get 0 rows when I would instead expect it to find every row.

So in the case where the operation is a NOT IN it would make sense to drop the condition completely.

[lann]

Thanks for the report; take a look at #100

[lann]

Had to revert the fix due to #101.

[lann]

New fix, now with 100% more regression test.

[Julusian]

I have just had a chance to test this and it appears to be working now.
Thanks